A dimmer including an optical element that controls the light transmitting state is known. The dimmer can block or open the view of a user by controlling two optical states, transmitting and scattering, and therefore the application and development to various uses including construction materials such as a room divider and an outside window are expected.
As a light control method used in the dimmer, liquid crystal dimming method (for example, Patent Literature 1), electrochromic dimming method, photochromic dimming method, and thermochromic dimming method (for example, Patent Literatures 2 and 3) are proposed.
The liquid crystal dimming is a dimming method that reversibly changes between the transparent state and the opaque state by inducing a change in orientation of liquid crystal molecules using voltage application. The electrochromic dimming is a dimming method that reversibly changes between the transparent state and the colored state using electrochemical reaction. The photochromic dimming is a dimming method that reversibly changes the colored state by the presence or absence of active ray irradiation.
The thermochromic dimming is a dimming method that controls the optical physics of materials by heat, and one of such method reversibly changes the transparent state and the opaque state using a clouding point phenomenon by aggregation or dispersion of molecules that occurs due to a change in temperature. Thermochromic materials include a liquid or gel material using aqueous solution with non-ionic detergents or non-ionic water-soluble polymers exhibiting the clouding point phenomenon by aggregation or dispersion, a material using semiconductor-to-metal phase transition such as vanadium dioxide and the like. Note that Non Patent Literature 1 is referred to in the embodiment described later.